Motor driven linear actuator and electric motor thereof

Abstract

A motor driven linear actuator comprises an electric motor, a ballscrew device, and a rolling bearing. The electric motor includes a motor shaft having a first end portion. The first end portion includes an end surface and a receptacle having a first accommodation space. The ballscrew device includes a screw having a first end portion coaxially connected to the first end portion of the motor shaft. The first end portion of the screw includes a first section to be accommodated in the first accommodation space for fixing the screw with the motor shaft. The rolling bearing is disposed between the electric motor and the ballscrew device for supporting the first end portion of the screw. The end surface of the motor shaft contacts and abuts against the rolling bearing for limiting the movement of the rolling bearing between the electric motor and the ballscrew device.

What is claimed is: 
     
       1. A motor driven linear actuator, comprising:
 an electric motor including a rotor, a stator and a motor shaft having a first end portion and a second end portion, wherein the motor shaft is integrally formed with the rotor, the motor shaft is extended from the rotor in a horizontal direction, the rotor includes a plurality of permanent magnets, the first end portion of the motor shaft is exposed outside one side of the stator and the permanent magnets in the horizontal direction, the second end portion of the motor shaft is exposed outside the other side of the stator and the permanent magnets in the horizontal direction, and the first end portion of the motor shaft includes an end surface and a receptacle having a first accommodation space; 
 a ballscrew device including a screw having a first end portion, wherein the first end portion of the screw includes a first section, the first end portion of the screw is coaxially connected to the first end portion of the motor shaft, the first section of the screw is accommodated in the first accommodation space of the motor shaft, and the first end portion of the screw is completely accommodated in the receptacle of the first end portion of the motor shaft for fixing the screw with the motor shaft; and 
 a rolling bearing disposed between the electric motor and the ballscrew device and configured to rotatively support the first end portion of the screw, wherein the end surface of the first end portion of the motor shaft contacts and abuts against the rolling bearing along the horizontal direction for limiting the movement of the rolling bearing between the electric motor and the ballscrew device. 
 
     
     
       2. The motor driven linear actuator according to  claim 1 , wherein the receptacle of the first end portion of the motor shaft further includes a second accommodation space, and the first end portion of the screw further includes a second section, wherein the second section of the screw is accommodated in the second accommodation space of the motor shaft for performing a concentric locating between the motor shaft and the screw. 
     
     
       3. The motor driven linear actuator according to  claim 2 , wherein a diameter length of the first accommodation space is larger than that of the second accommodation space, and a diameter length of the first section is larger than that of the second section. 
     
     
       4. The motor driven linear actuator according to  claim 2 , wherein the first accommodation space and the second accommodation space are coaxial with a rotation axle of the motor shaft, and the first section and the second section are coaxial with a rotation axle of the screw. 
     
     
       5. The motor driven linear actuator according to  claim 1 , wherein the electric motor is a servo motor. 
     
     
       6. The motor driven linear actuator according to  claim 1 , wherein the rolling bearing is an angular ball bearing, a deep groove ball bearing, a conical roller bearing, a cross roller bearing or a radial journal bearing. 
     
     
       7. The motor driven linear actuator according to  claim 1 , wherein the first accommodation space of the motor shaft has screw thread on an inner wall surface thereof, and the first section of the screw has screw thread on a portion of an outer periphery surface thereof, wherein the screw thread of the inner wall surface of the first accommodation space is threadably engaged with the screw thread of the outer periphery surface of the first section. 
     
     
       8. The motor driven linear actuator according to  claim 1 , wherein the first end portion of the motor shaft further comprises a screw and a screw through hole, wherein the screw is accommodated in and threadably engaged with the screw through hole, and an end portion of the screw abuts against the first section of the screw. 
     
     
       9. The motor driven linear actuator according to  claim 1 , wherein a fixing adhesive is disposed between the first accommodation space of the motor shaft and the first section of the screw. 
     
     
       10. The motor driven linear actuator according to  claim 1 , wherein the electric motor further includes a position sensor disposed at the second end portion of the motor shaft. 
     
     
       11. The motor driven linear actuator according to  claim 1 , further comprising a frame, and the ballscrew device is disposed in the frame. 
     
     
       12. The motor driven linear actuator according to  claim 11 , wherein the ballscrew device further includes:
 a carriage-nut threadably engaged with the screw, wherein the carriage-nut incorporates a plurality of rolling elements between the screw and the carriage-nut; 
 a table fixed to the carriage-nut for carrying a load thereon; 
 a linear bearing disposed in the frame and connected with the carriage-nut for limiting a rotation of the carriage-nut and guiding the carriage-nut to move along the screw; and 
 a supporting bearing disposed in the frame and configured to support a second end portion of the screw, 
 wherein the carriage-nut is moved along the screw when the screw of the ballscrew device is rotated by the driving of the electric motor. 
 
     
     
       13. The motor driven linear actuator according to  claim 1 , further includes a supporting member disposed between the electric motor and the ballscrew device for holding and securing the rolling bearing. 
     
     
       14. An electric motor for a motor driven linear actuator, wherein the motor driven linear actuator comprises a ballscrew device and a rolling bearing, and the ballscrew device includes a screw having a first end portion having a first section, the electric motor comprising:
 a rotor including a plurality of permanent magnets; 
 a stator; and 
 a motor shaft integrally formed with the rotor and having a first end portion and a second end portion, wherein the motor shaft is extended from the rotor in a horizontal direction, the first end portion of the motor shaft is exposed outside one side of the stator and the permanent magnets in the horizontal direction, the second end portion of the motor shaft is exposed outside the other side of the stator and the permanent magnets in the horizontal direction, and the first end portion of the motor shaft is coaxially connected to the first end portion of the screw, wherein the first end portion of the motor shaft includes an end surface and a receptacle having a first accommodation space for accommodating and fixing with the first section of the screw, the first end portion of the screw is completely accommodated in the receptacle of the first end portion of the motor shaft, and the end surface of the first end portion of the motor shaft contacts and abuts against the rolling bearing along the horizontal direction for limiting the movement of the rolling bearing.